The premise here being that a character who has fled to and eventually setting down in the Human world, rather than choosing to be a functional member of society like Sunset Shimmer, they choose a more "exciting" route. That being a life of Crime and Debauchery. way "cooler" than the boring life of a law abiding citizen.

When I say "crime" i mean engaging in lucrative but Illegal activities and operations that could land someone in a maximum security prison for decades or even for life while also spending the money gain from said shady activities on various vices and indulgences.

What would be your stab of your protagonist making such a terrible life choice?

A Canterlot noblepony turned corrupt, flees to the human world and ends up in an organised criminal operation...or bank heists.

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or even contributing to the creation of and peddling of various illegal substances and getting a share in the profits made from such shady operations.

I wonder how would the protagonist, whether it be an OC or any of the existing characters would encounter this shady individual.

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The 'Ocean's' films?